1. Field of the Invention
The present invention relates to a strap-band type connecting device which has a strap band provided to wind around a connecting portion between a tubular element and a metallic pipe with a predetermined winding force, and particularly concerns to a strap-band type connecting device in which a rod screw is rotatably provided within a housing.
2. Description of Prior Art
A strap-band type connecting device has a strap band provided to wind around a connector hose which serves as an article to be wound. In recent years, the connector hose has been used to vehicular air-conditioners which compress liquid refrigerant with high pressure. The connector hose also has been used to vehicular turbo-chargers which are exposed to high pressure with high ambient temperature. In order to cope with those adverse environments in which the connector hose is installed, high endurance properties have been required for the connector hose.
As one way to cope with the above adverse environments, it has been considered to increase a mechanical strength of the connector hose. For this purpose, the connector hose is reinforced with a hardness-increased rubber or shored up with an increased number of fibers embedded in the rubber.
As an alternative, the strap band is integrally formed with the connector hose by means of a synthetic resin so as to produce a glue-compound structure. The connector hose formed by the glue-compound structure requires a winding force higher than the ordinary rubber hose had needed. Various ways have been searched for seeking how to insure a stable winding force at the connector hose.
As a general structure of this type of strap band, an array of slit teeth is provided at one end side of the strap band, and a housing is provided at the other end side of the strap band.
Within the housing, the one end side overlaps with the other end side of the strap band, a rod screw engages its helical thread with the slit teeth. In combination with a rotational operation of the rod screw, the rod screw makes the one end side slide against the other end side of the strap band so as to tightly wind around the connector hose.
As examples of the strap-band type connecting device, prior art references disclose analogous devices. Among these prior art references, a first reference introduces a screw band (Laid-open Japanese Utility Application No. 07-44962). A second reference introduces a hose clamping device (Laid-open Japanese Utility Application No. 01-176293). A third reference introduces a hose clamp (Laid-open Japanese Patent Application No. 2003-28366). A fourth reference introduces a hose clip (Laid-open Japanese Domestic Patent Application No. 06-507465). A fifth reference introduces a clamping device for connection (Japanese Patent No. 4738328).
In the first through fifth references, a band has an accommodation portion called in turn as a winding portion, a housing, a housing portion, a casing and a housing, each of which rotatably accommodates a worm screw. The worm screw engages its helical thread tightly with respective bridged braces located between the neighboring slit teeth, so as to wind around the connector hose when the worm screw is rotationally operated.
Since the bridged brace is subjected to a reactionary force from the worm screw during the process in which the worm screw slides its helical thread on the bridged brace upon rotationally operating the worm screw, the reactionary force subjects the housing to a torsional force around the radial direction of the band.
Especially when a higher torque is applied accidentally to the rod screw, the bridged braces would be subjected to a larger amount of bending force from the helical thread. This leads to unfavorably deforming the housing to reduce the winding force, thereby resultantly loosen the band due to the deteriorated engagement between the helical thread and the bridged brace.
Therefore, the present invention has been made with the above drawbacks in mind, it is a main object of the invention to provide a strap-band type connecting device in which the housing is formed by a work-hardened bottomed frame, and the housing has a strength and rigidity higher enough to resist the torsional force exerted when the rod screw is rotationally operated, and making it possible for the housing to resist the torsional force with a sufficient strength and an improved durability even when the rod screw is rotationally operated accidentally with a magnitude more than an allowable amount of torque.